Brake issues- soft pedal ***updated with video***

Had some time on this today.

Issue still persists-

Bled (furiously I may add) several times and ABS cleared on inpa

Changed the master cylinder back to the original

Tapped and banged all lines

To be fair there was some residual air in the pipes

However of note- and checked against the coupe and Steve’s m54 z4- there is a hiss sound when pressing the pedal down

I am thinking now that it may be the vacuum servo at fault.

But thanks to all who have helped so far
 
Still trying to get to 100% with this.

It’s better but not right still.

What’s done:

As above

New fluid
New flexis
New vacuum booster
New master cylinder

I’m still getting softness at the start, which firms up with pedal pumping. If you then leave it 5-10 secs the softness returns

On other cars the pump action makes the pedal hard and it stays hard

The video shows the noises that are heard-

The next step I think is to change the dsc unit… I have one in the shed

Are they all interchangeable (this one is a pre facelift in the spare pile)

Any other ideas?

There are 100% no fluid leaks

Stuart
 
I have heard that if you remove a caliper, lift it, turn it so that the bleed screw is on the top, block the piston with a caliper retraction tool, it will help get the trapped air out.
 
Do you get the hiss sound with the engine running? With the engine off you may well get it as the residual vacuum in the servo is released - the pedal will also go harder at the same time.
 
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